The invention relates to a passenger gas bag protection device.
Known gas bags for the protection of passengers often have, as seen from the viewpoint of a passenger to be restrained by the device, a round outer contour in the inflated state, the width of which distinctly exceeds its height. These gas bags have a substantially oval outer contour from the viewpoint of the passenger (i.e. a view onto the front wall) and are to have an as large a restraint surface as possible, i.e. as large a front wall as possible, onto which the occupant strikes in the case of restraint. When the occupant sits too close to the instrument panel, the central region of the front wall, hereinafter named the center section, may hit the occupant, because this section is the one which is accelerated the most.
In driver""s gas bags there are already ideas to construct the center section as a depression, the center section of the front wall being permanently fastened on a circular area to the gas bag module. In this embodiment, in particular occupants sitting too close to the instrument panel are intended to undergo a safe restraint. The transfer of such designs for driver""s gas bags to passenger gas bags, however, entails the following problem: The passenger gas bags have a distinctly greater depth than the driver""s gas bags. Viewed from the side, the passenger gas bags in the inflated state have a shape which widens toward the occupant, i.e. the height of the gas bag constantly increases. If a circle area (center section) were now to be fastened permanently to the gas bag module, then it is to be expected that the depression widens towards the occupant in a funnel shape, whereby in the center of the front wall, however, a sufficiently large restraint area would not be available, if the occupant has the desired central sitting position.
The invention provides a passenger gas bag protection device which is distinguished by a good restraint of occupants sitting too close to the instrument panel and also a good restraint with a passenger sitting centrally. This is achieved in a protection device which comprises a gas bag which, in relation to an inflated state, has a rear wall and a front wall which front wall includes a center section and onto which a passenger strikes in the case of an accident. The gas bag, from a front view, i.e. a viewpoint of a passenger to be restrained by the device, has a round outer contour with a specific width and height in the inflated state. The width of the outer contour distinctly exceeds the height. In the inflated state the front wall has a depression mouthing to the outside in the manner of a slit. The slit runs in a direction of the width of the gas bag. A restraint means is provided and the depression is formed in that on inflation of the gas bag a center section of the front wall is prevented from a free movement outwardly by the restraint means. In the protection device proposed, the passenger gas bag likewise has an annular inflation chamber with a depression. However, the depression is constructed in the manner of a slit at the transition to the part of the front wall which is visible from the exterior, this construction permitting the upper and lower sections of the annular chamber to move towards each other and to touch each other, so that the front wall in the inflated state presents itself almost completely closed to the occupant, although the depression is still present.
According to the preferred embodiment, the gas bag is part of a gas bag module. A module covering closing the module is opened on inflation of the gas bag. The center section is fastened to the module by means of the restraint means beneath a part of the module covering, so that the module covering does not have to be swung outwards completely, but rather can remain in the region over the center section. The area of the module covering which is constructed as a flap can therefore be smaller than in the prior art, which reduces the deceleration values through the module covering which is to be swung up.
Preferably, the module covering therefore opens an oval annular outlet opening for the gas bag on inflation.
The gas bag is preferably defined by a gas bag wall which comprises the front wall, the gas bag wall having a continuous sheet of fabric which forms a back wall, the front wall and the depression and which is closed at the side. Through this construction, the gas bag wall can consist of as few individual parts as possible. The lateral closing of the continuous fabric sheet can take place on the one hand in that its edges are sewn and on the other hand in that on the side separate side walls are provided which are connected with it.
The closing of the depression preferably takes place by limiting straps adjoining the depression and provided inside the gas bag. The limiting straps are constructed so be so short that opposite wall sections of the depression contact each other in the inflated state of the gas bag and close the depression at least in sections.